The Aluminum Extrusion Process

What is an Aluminum Extrusion?

Aluminum extrusion is used to create lengths of aluminum of a fixed cross-sectional profile. Through extrusion, very complex cross-sections can be created with excellent strength and surface finish. The process of aluminum extrusion works by forcing a block of metal, known as a billet, to pass through the die opening of a smaller cross-sectional area than the billet itself.

Aluminum extrusion is widely used in construction, automobile and aircraft manufacturing, industrial machinery, and consumer goods.

The Extrusion Process

The extrusion process itself is a lot like the old Play-Doh Shape Maker. When you squeeze the Play-Doh through the press, the outgoing stream takes the shape of the selected mold. Similarly, the extruded aluminum assumes the shape of the die opening. By using powerful hydraulic presses capable of exerting up to 15,000 tons of pressure, aluminum can be extruded into any shape you could imagine.

There are two main methods of aluminum extrusion:

• Direct Extrusion
• Indirect Extrusion

Direct Extrusion

Direct extrusion is the most widely used method for aluminum extrusion. In direct extrusion, the die head is held stationary, and the aluminum billet is forced through the die using a moving ram.

Direct extrusion is commonly used in the manufacture of solid rods, bars, and hollow tubes. The design of the die can be modified to produce a wide variety of solid and hollow profiles.

Indirect Extrusion

In direct extrusion, it is the billet that moves. In indirect extrusion, the aluminum billet is held stationary, and the ram moves the die to exert pressure on the stationary billet. The advantage of keeping the billet stationary lies in keeping friction to a bare minimum.

Before extrusion starts, the cross-sectional shape is designed. The shape and features of the extruded metal are carefully calculated to maximize functionality, facilitate assembly, reduce weight, and minimize finishing costs. The unique characteristics of aluminum make it a cost-effective product with excellent functionality and a superb finish.

What is 80/20 Aluminum Extrusion?

80/20 aluminum extrusion is a modular framing system often referred to as “the industrial erector set.” This versatile system comprises aluminum profiles featuring T-shaped slots along their length, enabling easy assembly and reconfiguration of structures without the need for complex welding or permanent joining methods.

The 80/20 framing system was invented by 80/20 Inc., a company founded in 1989 by Don Wood and Bob Kyanka. It was designed based on the principle of using 20% input to achieve an 80% outcome, making it an efficient solution for building complex structures with minimal effort.

The Aluminum Extrusion Process

1. A die is cast from the cross-section of the desired shape.
2. Aluminum billets are heated in a furnace to a temperature of 750-925°F. At this point, the aluminum becomes a soft solid.
3. Lubrication, known as smut, is applied to the billet and ram. The smut is essential as it ensures the billet and ram do not stick together.
4. The ram applies pressure to the billet, pushing it through the die. During this process, liquid nitrogen is used to cool the die. The cooling prevents the formation of undesirable oxides, as well as prolonging the length of the die.
5. The extruded aluminum emerges from the die, taking on the same shape as the die opening. The extruded aluminum is pulled onto a cooling table where it is exposed to air, water, or a mixture of the two (depending on the final mechanical requirements of the metal).
6. Next, a stretcher is applied. This corrects any twisting that may have occurred and straightens the metal. Hardness and strength are improved during the stretching process.
7. The extrusions – which may be 50 meters long – are fed to a saw conveyor and cut to the required profiles using a circular saw.
8. For some aluminum alloys, an artificial aging process is applied to achieve optimal strength. Artificial aging is accomplished via precipitation heat treating in an aging oven. The aging process ensures the uniform precipitation of fine particles throughout the aluminum channel extrusions, enhancing their strength, hardness, and elasticity.
9. Finally, the finished profiles are taken to be finished or fabricated, ready to be shipped to the customer.

Benefits of Extruded Aluminum

Extruded aluminum has several advantages over other metals. Some metals can match some of the desirable characteristics of aluminum, but no metal can match all these benefits at once.

The benefits of aluminum extrusions are many and include:

• Aluminum is approximately one-third the weight of iron, steel, copper, or brass. This makes it easier to handle and more economical to ship. For this reason, aluminum is widely used in automotive design, aerospace, and high-rise construction.
• The strength of aluminum is sufficient for all but the most demanding of applications. Aluminum is very suitable for cold environments, as it gets stronger as temperatures fall.
• Resistant to corrosion. Aluminum doesn’t rust. It is protected by a surface film of oxide, and this protection can be enhanced through anodizing.
• Excellent thermal conductivity. Aluminum conducts heat better than most metals. This makes it ideal for heat exchanger operations. Extrusion can be used to produce shapes optimal for thermal conduction.
• The extrusion process is relatively inexpensive. Even prototypes can be made at a reasonable cost.

What is Aluminum Extrusion Used For?

The unique combination of strength, light weight, and corrosion resistance makes aluminum extrusions an ideal choice for numerous applications. Let’s examine some of the most significant applications of aluminum extrusion profiles across various industries.

Aerospace Industry

In aerospace applications, aluminum extrusions are critical components where weight reduction directly impacts performance:

• Aircraft frames and structural components
• Wing components
• Interior components, including seating frameworks
• Support structures

Automotive Applications

The automotive industry relies on aluminum extrusion for enhancing vehicle performance and sustainability:

• Structural components, including frames and chassis elements
• Side-impact beams and roof rails
• Heat exchangers and radiators
• Interior trim and mounting brackets

Building and Construction

Aluminum extrusions have become a staple in modern construction:

• Window and door frames
• Curtain wall systems for commercial buildings
• Structural supports and framing systems
• Railings, staircases, and architectural accents

Electronics Industry

The electronics sector benefits from aluminum’s thermal properties and formability:

• Heat sinks and thermal management components
• Electronic enclosures that provide EMI shielding
• Computer and device chassis
• Precision components for electronic assemblies

Manufacturing and Industrial Applications

In manufacturing settings, aluminum extrusions serve both structural and functional roles:

• Modular T-slot framing systems, like 80/20 aluminum extrusion, for workstations
• Conveyor system frameworks
• Machine guards and safety enclosures
• Assembly line structures that can be reconfigured as production needs change

Consumer Products and Furniture

Beyond industrial applications, aluminum extrusions appear in everyday items:

• Bicycle frames and components
• Furniture frames and supports
• LED lighting housing and fixtures
• Display systems and retail fixtures

Metal Supermarkets is your source for aluminum extrusion profiles in a variety of shapes and sizes. Our team is ready to help you find exactly what you need, whether you’re wondering where to buy aluminum extrusion materials, need advice on how to cut aluminum extrusion, or are trying to determine which aluminum extrusion profiles will work best for your application. Visit your local Metal Supermarkets today to explore our selection of aluminum extrusions.